3d identification filter

Abstract

A 3D identification filter ( 101 ) is provided, which has a passband partially overlapping with a wavelength range of 800 nm to 1800 nm and a blocking band containing a range of 380 nm to 750 nm, and comprises a substrate ( 102 ) and filter film layers ( 103, 104 ) coated on both surfaces of the substrate, wherein the filter film layer ( 103 ) on one of the surfaces is composed of high refractive index layers, medium refractive index layers, and low refractive index layers that are stacked, and the filter film layer ( 104 ) on the other surface is composed of at least two layers of materials that are stacked. The 3D identification filter ( 101 ) maintains a high bocking level and a narrow transition band while achieving a small wavelength shift at a large light incident angle.

1 . A 3D identification filter having a passband partially overlapping with a wavelength range of 800 nm to 1800 nm and a blocking band containing a wavelength range of 380 nm to 750 nm and comprising a substrate and filter film layers coated on both surfaces of the substrate, wherein
 the filter film layer on one of the surfaces is composed of high refractive index layers, medium refractive index layers, and low refractive index layers that are stacked; the high refractive index layers are Si:H, and the refractive index of each high refractive index layer at 800 to 1800 nm is greater than 3; the refractive index of each medium refractive index layer at 800 to 1800 nm is greater than 1.6 and less than 3; the refractive index of each low refractive index layer at 800 nm to 1800 nm is less than 1.6; and the ratio of total physical thicknesses of all high refractive index layers and all low refractive index layers is greater than 1.5:1; and   the filter film layer on the other surface is composed of at least two layers of materials that are stacked, and the number of layers is not less than 15; the passband of the filter has a center wavelength that shifts less than 20 nm when the angle of incident light changes from 0 degree to degrees; a blocking level of the blocking band of the filter for the range of 380 nm to 750 nm is greater than OD4; and the edge of the passband of the filter is provided with a transition band, and the width of the transition band from 90% transmittance to 10% transmittance is less than 5 nm.   
     
     
         2 . The 3D identification filter according to  claim 1 , wherein the material of the substrate is a silicon material, or a glass material based on silica, or plastic, or sapphire. 
     
     
         3 . The 3D identification filter according to  claim 1 , wherein the passband has a center wavelength, and when the angle of incident light changes from 0 degree to 30 degrees, the shift of the center wavelength is less than 12 nm. 
     
     
         4 . The 3D identification filter according to  claim 1 , wherein the medium refractive index layer is one of Si:H, TiO 2 , Nb 2 O 5 , Ta 2 O, SiO 2 , and Si x N y  or a mixture of at least two of them and when it is a mixture, the refractive index thereof has a property of being continuously adjustable in a range from 1.6 to 3 through process proportioning;
 or the medium refractive index layer is SiO x :H, and the refractive index thereof has a property of being continuously adjustable in the range from 1.6 to 3 through process adjustment of stoichiometric ratio of element components;   or the medium refractive index layer is SiN x :H, and the refractive index thereof has a property of being continuously adjustable in the range from 1.6 to 3 through process adjustment of stoichiometric ratio of element components.   
     
     
         5 . The 3D identification filter according to  claim 1 , wherein the low refractive index layer is SiO 2 . 
     
     
         6 . A method for manufacturing the filter according to  claim 4 , wherein the method is a mode of mid-frequency magnetron sputtering or ion beam sputtering to form a Si:H film layer by introducing hydrogen into a sputtering system. 
     
     
         7 . The method according to  claim 6 , wherein the flow rate of hydrogen can be regulated to adjust the optical properties of the Si:H film layer. 
     
     
         8 . The method according to  claim 6 , wherein the flow rates of hydrogen and oxygen can be simultaneously regulated to adjust the stoichiometric ratio of element components of a SiO x :H film layer, and then adjust the refractive index of SiO x :H. 
     
     
         9 . The method according to  claim 6 , wherein the flow rates of nitrogen and hydrogen can be simultaneously regulated to adjust the stoichiometric ratio of element components of a SiN x :H film layer, and then adjust the refractive index of SiN x :H. 
     
     
         10 . The method according to  claim 6 , wherein at least two layers of materials can be co-deposited, and the refractive index of the mixture film layer is adjusted by adjusting the ratio of the materials.